<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <p>
      <input type="text" name="a" />
    </p>
    <p>
      <input type="file" name="img" accept="image/*" multiple />
    </p>
    <p>
      <button>提交</button>
    </p>
    <img src="" alt="" />
    <script>
      function upload() {
        const inpA = document.querySelector("[name=a]");
        const inpFile = document.querySelector("[name=img]");
        const img = document.querySelector("img");
        const formData = new FormData(); //帮助你构建form-data格式的消息体
        formData.append("a", inpA.value);
        for (const file of inpFile.files) {
          formData.append("img", file, file.name);
        }

        fetch("/api/upload", {
          body: formData,
          method: "POST",
        })
          .then((resp) => resp.json())
          .then((resp) => {
            console.log(resp);
            if (resp.code) {
              //有错误
              alert(resp.msg);
            } else {
              img.src = resp.data;
            }
          });
      }

      document.querySelector("button").onclick = upload;
    </script>
  </body>
</html>
